Occasionally the pan motor will cause the camera to point to the left or to the right when you want it to be centered. The way to fix this depends on the firmware version you are using. (Note: this post does not apply if your Helix is moving around erratically on the pan axis.)
Helixes with firmware version 2.43 b6 or earlier
For these Helixes, the key is to change the offset value for the pan axis (on the follow tab of the SimpleBGC GUI) until the Helix maintains a centered position. You can also do this using the orientation/calibration screen in the iOS app.
Helixes with firmware version 2.55 b9 or later
For these Helixes, turn on the Helix, then hit the Menu button once to turn off the motors. Then move the pan axis so that the camera is centered properly. Reset the Helix (hold the Menu button down for 5 seconds), and it should stay in this position. If you have done this a few times without success, you may have a problem with the pan follow offset value (on follow tab in the SimpleBGC GUI or on the orientation/calibration screen of the iOS app. Make sure this value is set to zero. Then reset the Helix while holding it in the centered position.